Lubricating oil compositions having extreme pressure characteristics



United States Patent 2,987,478 LUBRICATING OIL COMPOSITIONS HAVING EX- TREME PRESSURE CHARACTERISTICS Howard J. Matson, Harvey, Ill., assignor to Sinclair Reg lmng Company, New York, N.Y., a corporation of awe No Drawing. Filed Jan. 26, 1959, Ser. No. 788,768 7 Claims. (Cl. 252-464) My invention relates to a superior lubricating oil composition. More particularly the invention is directed to a novel lubricating oil composition having improved extreme pressure and anti-friction properties.

With the advent of high compression internal combustion engines, much difiiculty has been experienced in formulating a suitable lubricating oil composition capable of operating under severe conditions to protect efifectively metal surfaces which come in contact with the oil. It is well known that the high pressure occurring in certain types of gears and bearings may cause a film of lubricant to rupture with subsequent damage to the machinery. It has been shown that base lubricants such as mineral oil and/or synthetic oil can be improved with regard to their protective effect on surfaces by the addition of certain substances so that excessive wear, scuffing and seizure which normally follow a break in the film of lubricant can be prevented even under the most unfavorable pressure and speed conditions. Lubricants possessing this highly desirable property are called extreme pressure lubricants.

Certain classes of compounds can be used to improve specific properties of base lubricants. Thus, compounds containing sulfur, chlorine, phosphorus or lead or combinations of these elements may improve the extreme pressure properties of a lubricant. However, the simple presence of these elements does not guarantee extreme pressure properties and various compounds that do have these properties can vary considerably in their effectiveness. It is generally believed that the effectiveness of an extreme pressure additive is related to its ability to react with and form a protective coating on a bearing surface to be lubricated. T o be most effective, however, the additive must be present in sufiicient concentration at the surfaces to form an adequate film. One method of realizing this surface concentration is the use of polar or other type molecules which have an aflinity or attraction for surfaces. Thus, as opposed to the use of a non-polar molecule which will be present in more or less equal concentration throughout the bulk of the lubricant, a polar type molecule will tend to give a greater concentration of additive at the metal surface where it is needed.

The use of molybdenum as a lubricant particularly in the form of molybdenum disulfide has increased as those skilled in the art have found this material to have outstanding lubricating characteristics. Compounds such as boron nitride, cadmium iodide and graphite have a suitable crystal structure but fail in other respects to meet necessary extreme pressure requirements. Further-boron nitride does not have any aflinity to metal surfaces; cad- "ice mium iodide is effected by moisture; and graphite has a low afl'inity to metal surfaces; thus it depends on ab sorbed gases or liquids for its lubricating characteristics. Over the years the chemical industry has been faced with the difiiculties of adding a suitable solid such as molybdenum disulfide to a fiuid lubricant which normally results in settling, plugging of narrow orifices, cleavance of lines, valve sticking, ring clogging and the like. My composition overcomes these difiiculties while obtaining lubricating advantages from a molybdenum material.

My invention is directed to a lubricating oil composition consisting essentially of a major amount of lubricating base oil, a minor amount of molybdate ester and a sulfurized fatty oil or a sulfurized olefin.

The esters of my composition are the base-oil compatible, i.e. soluble, dispersible or miscible, aliphatic monohydric alcohol esters of molybdic acid. The aliphatic ester radicals in general contain at least four carbon atoms and preferably are saturated with from one to all of the ester groups containing 8 to 20 carbon atoms. The amount of ester added to the base oil may vary depending upon particular characteristics required although suflicient ester must be present to give the desired effect. In general from about .1% to about 10% of ester by weight of afinal composition is used with about 1 to 5% being preferred. The alkyl esters of molybdic acid which are employed in the lubricatingoil compositions according to this invention are conveniently prepared by the usual reactio'ns. The mixtures of reactants are ordinarily heated to accelerate esterification. For present purposes, the alkyl esters of molybdic acid or alkyl molybdates, as they are commonly called, are preferably prepared by the reaction of an aliphatic alcohol and molybdenum compounds such as molybdic anhydride o'r molybdenum trioxide, ammonium molybdate, ammonium paramolybdate and molybdanyl chloride. As an example, the reaction product can contain about 2 moles of alcohol radical for every mole of molybdenum trioxide.

The alcohols which are generally reacted with the molybdenum compounds referred to above are aliphatic alcohols containing up to 20 carbon atoms. The aliphatic radicals may be straight chain or branched chain or cycloaliphatic in nature. Either primary, secondary or tertiary radicals are suitable, but primary and secondary radicals are preferred for desirable physical properties in the base oil and apparent efiectiveness. Examples of these'alcohols include n-butyl alcohol, tertiary butyl alcohol, n-hexyl alcohol, cyclohexyl alcohol, n-octyl alcohol,

'2-ethylhexanol, isooctyl alcohol, decyl alcohol, dodecyl alcohol, tridecyl alcohol, octadecyl alcohol, etc. or their mixtures. Higher aliphatic alcohols are preferred, the term here being used in its commonly accepted sense as covering alcohols of eight carbon atoms or more. Such alcohols impart desirable physical characteristics to the alkyl molybdates prepared from them. Branched chain alcohols, for example, those derived by the well known 0x0 process are particularly suitable. Decyl and tridecyl alcohols of this latter type have been found to be r g 3 effective. My molybdate esters-may have structures such 25':

derivatives such as the propylene oxide polymers andtheir'ethers and esters in which the terminal'hydroxyl groups have been modified are also suitable. Synthetic QH KEf oils of the dicarboxylic acid diester type including di- Mo Mo 5 butyl adipate, di-2-ethylhexy1sebacate, di-n-hexyl fumaric R R polymer, di-lauryl azelate, and the like may be used alone or in blends containing complex or polyesters or other and thickening agents. These esters are frequently made from dibasic acids, alcohols and glycols of 6 to 12 carbon 03 atoms. Alkyl benzene types of synthetic oils such as RO\CH)/O\ I O 0R tetradecyl benzene, etc. are also included.

M0 M0 M0 The extreme pressure compositions of this invention l are eifective in the form of compounded lubricating oils O 15 containing conventional additives such as oxidation inhibitors, detergents, VI improvers, antifoaming agents, where R0 i th l h l di L rust inhibitors, oiliness or film strengthening agents, wear 'My' composition can contain a base-oil compatib e inhibitors, dyes and the like. Base-oil compatible chlosulf rized'fatty Oil such as sulfurized Sperm oil, sulfurized rmated hydrocarbons can be included in my compositions rape seedoil, sulfurized cotton'seed'oil, etc. These oilsv without causing the high wear that frequently accomin general are esters and glycerides of acids of 12 to 24 panics their use. A typical chlorinated hydrocarbon is carboniatoms. A particularly eifective material employed a product usually containing about 25 to 75% hlorine 1S .sblfill'lled Sperm 011 which cofltalns about 5 to 15 by weight and made by the reaction of gaseous chlorine Welsh? Pement of combmefi Sulfurgeneral from with high-boiling saturated or unsaturated aliphatic hyg g rlercent .sulf'inzed'fatty about 3 25 drocarbons, including cycloaliphatics, of say 8 to 32 car- 0 E Q llstenployed gf ig bon atoms. The materials are used in amounts similar amoun emguom a on o percen yweig o e to my sulfurized olefin final composmon' The ester of the resent invention ma be re ared Anothersulfur-containing material useful in the present b various convenfignal means suflh as f .5 invention is a base oil-compatible sulfurized olefin hydroy 1 I 1 carbon. This sulfurized olefin is usually prepared by the amp e reactionof an aliphatic olefin, preferably branched chain, EXAMPLE I of 8-32. carbon atoms with sulfur and'comprises about 25-75% sulfur by Weight; Although sulfurized hydro- 1800 grams of tridecanol (OH value'=279) and 750 carbons having as little as 10% sulfur by weight are 35 ml. of toluene as solvent were placed in a 5-liter reaction sometimes used, the more highly sulfurized materials, flask. 200 grams of M00 were dissolved in 4 liters of in an amount from about 0.1 to preferably about H 0 and 350 1, of NH OH. A nitrogen t o h r t0 2%, y Weight of lubl'lcani qomposltwn was supplied to the reaction flask. After heating the alcomost often p y to glve a fully satlsfacfory hol solution to about 110 C., the molybdate solution Purpose matenal- AS i 3 2 sulfunzed hydro was added slowly over a period of 5 hours with constant carbon may 3 matenall m g g hyikocarbgn'has stirring in a 105110 C. temperature range. Water was a .Stmcure to or PO 3,450 my me an constantly removed, and reaction was continued for 48 @m i out 1 0 th f 1 b fn Vscosit hours, gradually increasing the reaction temperature to e.natura an e m 018 o meal g y 250 C. The product was then filtered, recovering the are sultable base oils for the compositions of the inven- 4.)

sohds, and the solvent and excess alcohol removed by tron. They include hydrocarbon or mineral lubricating {11 t 150 c 850 f d t oils of naphthenic, paraflinic, and mixed naphthenic and vacuum is 1 a 2i 1: grams 0 P paraffinic types They may be refined by any of the com were recovered w c analyzed to be 14.8% of molybventional methods such as solvent refining and acid redemlm by Welgbtfi i synthetic hydrocarbon 11 f h alkylene 5 The data of following Table i demonstate the increased ol me type 1- tho e derived from oal and shale may extreme pressure and anti-wear properties of my comalso be employed. Alkylene oxide polymers and their position.

Table I Weight Percent Composition:

SAE 90 Mineral Gear Oil, 82.5 SUS at 210 F 100 98 09. 5 99. 5 0s 90 97. 5 95. a Sulfurized Sperm Oil (12% S) 2 2 2 Sulfurized Hydrocarbon 1 (46% S). 0.5 0. 5 Chlorinated Hydrocarbon 2 (50% Cl) 0.5 0.5 Tridecanol Molybdate Ester ...-1 2 2 2 2 Laboratory Tests:

Viscosity, SUS- at 100 F 933 963 920 933 915 934 928 009 at 210 F- 32.5 84.7 81.8 82.4 82.2 84.2 82.4 7 Viscosity Trifle! 92 89 89 91 93 9O Pour, F 0 5 0 5 5 0 0 5 Percent Sulfur 0.24 0.23 0.24 0.23 0.24 Percent Chlorine..- 0. 25 0.25 Percent Molyb m 0.18 0.18 0.18 0.18 Performance Evaluation:

Timken Safe Load, lbs 7 20 30 10 7 15 30 27 Falex Breakdown, lbs 1,250 3, 500 4, 500 1,000 3, 250 4,500 4, 500 4,500 SAE at 300 r.p.m., lbs 348 374 397 141 347 381 412 Shell 4-Ball Wear Test, mm. scar (7 Kg., 2 Hrs, 0.,

640r.p.m.) 0. 55 0. 33 0. 3s 0. 64 0. 37 0.39 0. 30 0. 41 Shell 4-Ball EP Test- Weld, m: 141 17s 17s 153 141 200 22 224 Mean Hertz Load 13.8 34.7 37.5 27.5 25.4 49.7 40.7 43.3

7 i 1 Molybdate ester of trideeanol, see Example I.

5 Table II indicates more detailed data on the Falex breakdown load or low carrying capacity tests as shown in Table I.

3. The lubricating composition of claim 2 which contains sulfurized sperm oil.

Table II Weight Percent Composition:

SAE 90 Gear Oil 100 98 99. 5 99. 5 98 96 97. 5 95. 5 Sulfurized Sperm Oil (12% S) 2 2 2.0 Sulfurized Hydrocarbon 1 (46% S) 0. 5 O. 5 Chlorinated Hydrocarbon 2 (50% O1) 0.5 0. 5 Tridecanol Molybdate Ester L 2 2 2. 0 2. 0 Falex Breakdown Load, lbs 1, 250 3, 500 4, 500 1, 000 3,250 4, 500 4, 500 4, 500 Torque at:

500 lbs. load 11 10 11 11 12 11 7 10 1,500 lbs. load 23 50 23 14 12 14 2,500 lbs. load 34 57 70 27 33 3,500 lbs. lnari 73 34 26 38 4.500 lbs. l 78 30 38 Temperature at:

500 lbs. load 162 160 165 179 167 178 148 168 1,500 lbs. lnad 214 304 215 208 173 198 2,500 lbs. load 257 386 341 280 237 267 3,500 lbs. h 420 468 309 272 325 4,500 lbs. l 507 328 294 340 Sainim Weld Weld None Weld None None None None Wear Heavy V. Heavy Light Med. Med. Ridging- Heavy Coarse Fine Med. Fine 3 See Table I.

The following data indicate the advantages of using my compositions wherein the base oil is a synthetic lubricant.

4. The lubricating composition of claim 2 which contains sulfurized polyisobutylene.

Table III Weight Percent Composition:

Base Oil 1 100 96 98 98 Molybdate Ester 2 2 0 Sulfurized Sperm Oil (12% B) 2 0 2 Tests:

Viscosity at- 100 F., cs 13.04 14. 25 13.27 13.78 210 F 3.444 3.625 3.488 3. 609 Viscosity Index 162 160 163 168 ASIM Slope SAE at 300 r.p.m., lbs 31 335 110 227 Shell 4-Ball Wear Test (7 K Hrs., 11 0.,

640 r.p.m.) 0. 51 0- 0. 42 0. 47 Shell 4-Ball EP Test- Weld, Kn 141 200 141 178 Mean Hertz Load. 21. 0 44. 6 38. 6 28. 5

1 Di-2-ethylhexyl sebacate with 0.1% free sebacic acid (Plexol-201J). I Molybdate ester 01' tridecanol of Example I.

Tables I, 11 and HI clearly demonstrate the improved 5 5. The lubricatmg composition of claim 2. in which the lubricating properties of my new composition where a sulfurized fatty oil or sulfurized olefin is used in conjunction with molybdate esters in mineral or synthetic lubricating oils to produce superior extreme pressure and antiwear properties.

I claim:

1. A lubricating composition consisting essentially of a major amount of a base oil of lubricating viscosity, about .I% to 10% by weight of a base oil-compatible aliphatic monohydric alcohol ester of molybdic acid, said alcohol containing 4 to 20 carbon atoms and about 0.5 to 15% by weight of a base oil-compatible member selected from the group consisting of sulfurized fatty oils and sulfurized olefins of 8 to 32 carbon atoms.

2. The lubricating composition of claim 1 in which the ester of molybdic acid is present in an amount of about 1 to 5% and the member selected from the group consisting of sulfurized fatty oils and sulfurized olefins which is present is about 1 to 8% when a sulfurized fatty oil and about .1 to 5% when a sulfurized olefin.

References Cited in the file of this patent UNITED STATES PATENTS 2,203,507 Roehner et a1. June 4, 1940 2,208,161 Prutton et a1. July 16, 1940 2,291,404 Morway July 28, 1942 2,805,997 Benoit et al Sept. 10, 1957 OTHER REFERENCES Extreme Pressure Lubricants, Lubrication, pubd by The Texas 00., New York, N.Y., vol. XLIII, No. 6, June 1957, pages -76. 

1. A LUBRICATING COMPOSITION CONSISTING ESSENTIALLY OF A MAJOR AMOUNT OF A BASE OIL OF LUBRICATING VISCOSITY, ABOUT .1% TO 10% BY WEIGHT OF A BASE OIL-COMPATIBLE ALIPHATIC MONOHYDRIC ALCOHOL ESTER OF MOLYBDIC ACID, SAID ALCOHOL CONTAINING 4 TO 20 CARBON ATOMS AND ABOUT 0.5 LECTED FROM THE GROUP CONSISTING OF SULFURIZED FATTY OILS AND SULFURIZED OLEFINS OF 8 TO 32 CARBON ATOMS. 